Get out of bed on the wrong side
Definition 1 of 1
Pro Tip 1/3Cultural Origin
This phrase comes from a superstition that waking up on the left side of the bed is bad luck. 
Did you wake up on the left side today? You're so irritable.
Pro Tip 2/3Expression of Mood
Use this phrase to describe someone's unusually bad mood, not just minor irritation. 
Watch out for the boss, he got out of bed on the wrong side this morning.
Pro Tip 3/3Humor Tone
The phrase is often used humorously to lighten the mood when someone is grumpy. 
Uh oh, looks like Mike got out of bed on the wrong side today!